Determination of selenium in the human brain by graphite furnace atomic absorption spectrometry

Abstract

For the investigation of neurological disorders, a development of simple and accessible methods for determining selenium in human brain samples is required. We devised a method of determining selenium using graphite furnace atomic absorption spectrometry (GFAAS). An electrodeless discharge lamp provided the sufficient sensitivity to determine brain selenium. The matrix interferences were avoided by using high temperature, a prolonged pyrolysis step, and a palladium matrix modifier. The technique of standard addition was used to evaluate the sample concentrations. The accuracy of the method was confirmed by a bovine liver reference material. The detection limit of selenium was 0.04 ng. The determined selenium concentrations of human brain cortex and white matter were higher than those of putamen (115-155 and 206-222 ng/g wet wt, respectively). These GFAAS values agreed with those obtained by fluorometric analysis (r = 0.91, n = 10). Moreover, the GFAAS values were compatible to those reported by other researchers (99-274 ng/g wet wt), in which selenium concentrations in putamen also tended to be higher than the other two regions. We conclude that GFAAS is useful for selenium analysis in brain samples.

The Chemical Nature of Mercury in Human Brain Following Poisoning or Environmental Exposure

“…In all cases, we find that this organic selenium is close to 3.5 μM and is divided between selenyl sulfides and organic selenides (Table 2). Our value of 3.5 μM is close to total selenium levels in brain previously reported by others (34). If the selenium depletion hypothesis (24) were correct, then some decrease in this organic selenium might be expected in cases 1 and 2.…”

Comparative Analysis of Selenocysteine Machinery and Selenoproteome Gene Expression in Mouse Brain Identifies Neurons as Key Functional Sites of Selenium in Mammals

“…However, during Se deficiency, the brain shows an ability to preserve this trace element, whereas other organs readily lose Se (13,15,46). In addition, several studies revealed that the regions of human brain enriched for gray matter tend to have higher Se levels, whereas white matter was found to have reduced Se, and Se appeared to concentrate in glandular parts of the brain (41,44,47). Similar patterns were observed for animals (48,49).…”

“…Numerous studies have examined the levels of Se in human and animal tissues and found an uneven distribution of this trace element (41)(42)(43)(44)(45). Se content of human brain (ϳ88 ng/mg wet weight) is much lower than that of kidney and liver (ϳ469 and ϳ221 ng/mg wet weight, respectively (45).…”

Role of Selenium on Calcium Signaling and Oxidative Stress-induced Molecular Pathways in Epilepsy

“…Firstly, regions containing more gray matter tended to have higher selenium levels and were highest in putamen (1,093 ng/g dry weight) [28], but much lower levels of Se were present in white matter (for example, 283 ng/g in Corpus callosum). In a Japanese study, the selenium level was 115-155 ng/g wet weight in brain cortex and white matter, and 206-222 ng/g in putamen [29]. All part of the brain and nervous system contain Se-dependent GSH-Px and thioredoxin/peroxiredoxin system [11].…”